A lot of emphasis is currently placed on the need for principals to be instructional leaders or leaders of learning. In the study of the instructional leadership of secondary principals reported in this article, the authors argue that instructional leadership can be both direct and indirect. Direct instructional leadership is focused on the quality of teacher practice itself, whereas indirect instructional leadership creates the conditions for good teaching. Indirect instructional leadership is particularly important for secondary principals because much of the direct leadership is carried out by deputies and heads of department. The authors found that, when looking at the achievement results of the school as a whole, different instructional leadership behaviours predicted high performance and improvement.